Although pixel-wise losses, i.e., L1 and MSE loss, have been widely used to achieve high image quality, they do not capture the perceptual differences between the SR and HR images. In order to address this problem and allow the loss functions to better measure the perceptual and semantic differences between images, content loss, texture loss, and targeted perceptual loss are proposed. Among them, content loss has been widely used to obtain more perceptual and natural images [1]}, [2]}, [3]}, which has been introduced in Sec. REF . Apart from obtaining more similar content, the same style, such as colors, textures, common patterns, and semantic information are also needed. Therefore, other perceptual loss need to be considered.
